This is topic Paint Question on Alumicore in forum Letterhead/Pinstriper Talk at The Letterville BullBoard.


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Posted by Rusty Bradley (Member # 6938) on :
 
Since I don't paint on alumicore I'm going to ask you guys for some help...an artist friend of mine was using heavy rolled steel to do a series of exterior murals...she was paying like a $1,000 for these pieces that were roughly 4'x 8's...I suggested she try alumicore for under a $100...I work only in wood and hdu so I'm not familiar with painting the material...but I suggested that she rough the surface of the alumicore and prime it before painting...she did this and then painted with Ronan acrylic...she just called and said that after 5 days of drying she is having a problem...as I understand she scratched up the paint a bit on an edge and then was able to peel off sections of the paint which now has her freaked out...the paint was not peeling up on it's own...she did manually scratch the paint up and then peeled it off...I'm wondering whether or not there is a problem...and if there is then what would her problem be.
 
Posted by old paint (Member # 549) on :
 
DID SHE REMOVE THE PLASTIC FILM....... before she painted on it???
 
Posted by Kelly Thorson (Member # 2958) on :
 
If it is very humid out it may take quite a while for the paint to dry. What did she use to prime the panels?
 
Posted by Rusty Bradley (Member # 6938) on :
 
Kelly...the panel is still in her studio...it has not been outside...she primed with Kilz.
 
Posted by Preston McCall (Member # 351) on :
 
Kilz? Huh. I have painted on alumicore for years both fine art and signs. Sticking latex to it was never a good idea to me and I always used an oil based primer and paints. Excellent adhesion.

For the latex, I imagine no amount of scuffing will cause it to stick hard, but after a month or so of drying it probably will actually stick better than anything else. Time seems to be the cure for her ills. Maybe sun bake them for a faster set up? never tried hardener in latex but who knows? I used it by accident years ago with acrylic lacquer, against any manufacturers recommendations and it worked so well they eventually encouraged it, but isocyanate hardener is kinda expensive and does require proper ventilation. Anybody ever tried it in latex?
 
Posted by Rusty Bradley (Member # 6938) on :
 
Preston...I'm thinking the same...with time it will adhere just fine...she will also be having a anti UV coat sprayed on it...I'm thinking had she not messed with it this worry would never had occurred.
 
Posted by Dave Sherby (Member # 698) on :
 
First, I've never been a big fan of Kilz. Second, when I painted this type of panel many years ago, (at least 6 years ago) all I did was scuff the surface and top coated, no primer at all. These panels had both paint and vinyl on the latex (Porter paint) and I just saw them last week and they still look like the day I installed them. I was pretty leery on this job as it was the first time I had used latex on an aluminum panel, but after seeing this sign many times per year, and seeing no peeling or fading, I feel much better. I have read that latex can take 30 days to fully cure and on a non porous substrate like aluminum, it really does take a while before the paint grips tightly.
 
Posted by Si Allen (Member # 420) on :
 
I agree with Old Paint ... did she remove the protective film?
 
Posted by old paint (Member # 549) on :
 
IF SHE TOOK OFF THE PROTECTIVE FILM.......
THEN SHE SHOULDA .........treated it like any other METAL!!!!!
1. USE Automotive primer!!!!! NOT KILZ!!!
2. USE Automotive PAINT... for over all color.
3. NOW..... the surface your painting on is the same as.A NEW VEHICLE.....the background paint will outlast any vinyl or paint you put on it.
I KNOW THIS....because i have been doing this process when MDO was the only form of sub-straight!!!! AUTOMOTIVE PAINT/PRIMER has a hotter vehilce for its primer/paint which causes the paint to BITE..and ADHERE to under layment surface........THUS A BETTER BOND of paint to surface.
 
Posted by Dale Feicke (Member # 767) on :
 
Rusty, we have had some big changes in these panels, in the last year or two. Like Dave said, the older ones were baked enamel, and scuffing and painting would give a great job....used them for years.

These new panels have a very slick coating, called PVDF. It's very, very thin (easy to sand through) and very tough. But...it's designed for outdoor commercial applications, to be resistant to stains, chemicals, bird doo-doo, etc. The person at the vendor told me, "It's made so that not much of anything will stick to it."

I've had adhesion issues with it too, both oil base and acrylic. And no real answers in sight. Except for applying vinyl.

[ July 08, 2014, 02:19 PM: Message edited by: Dale Feicke ]
 
Posted by Dave Sherby (Member # 698) on :
 
Well Dale, if that's the case we should find out if any of the brands don't use the PDVF coatings because not being able to paint on a panel is just not acceptable.
 
Posted by old paint (Member # 549) on :
 
AUTOMOTIVE REDUCERS AND THINNERS.......WILL.. bond paint to that)))))))))))))i never have paint peel........because i use automotive paint.
 
Posted by Dale Feicke (Member # 767) on :
 
I'm not doubting ya, Joe. Lots of automotive products are fine; but get your checkbook out. They prices on this stuff are astronomical. Each different product (primer, basecoat, topcoat) has its own thinners and hardeners...no intermixing.

But Dave, it might bear some research anyway. I've used oil and acrylics on this stuff, and the only thing I've had any real success with sticking fairly well, is using acrylic enamel hardener in my lettering paint. That's after LIGHT scuffing with a fine scuff pad. Any more than that, you'll go thru the coating, or the scuff marks will really show. I'm not real fond of this stuff.
 
Posted by old paint (Member # 549) on :
 
the cost on automotive......is in line with anyo there paints.
the difference is..........when you buy a quart of auto body paint..........when reducer is added, you now have 2 QUARTS OF PAINT.... ))))))) automotive paint is heavier with "solids" and that is why a quart seems expensive. with regular off the shelf paint.......that is ALREADY THINNED to working viscosity)))))
and if you have spray gun/compressor, you can do it faster and get a better finish then any roller or brush.
the car paint companies what you to belive....EACH PAINT HAS TO HAVE ALL THE SAME PRODUCTS... its a selling point......BUT NOT TRUE......sherwin williams A/E auto paint, thinners, reducers catalyst, hardners.... will work in NAPA, DUPONT, SIKKENS.....as long as they are ACRYLIC ENAMEL))))) URETHANES same thing.....brand dont matter all the same chemicals.......
 
Posted by Bill Diaz (Member # 2549) on :
 
All you have to do with prepainted aluminum clad
panels such as Alupanel, Alumalite and just straight
aluminum that is already painted and ready for vinyl, is scuff it up with (red) Scotchbrite and paint it with 100% acrylic house paint.

After you scuff it, rinse it with rubbing alcohol and tack rag it off. Use a good quality 1/4" nap roller cover to roll the background on.

All the paint technology has gone towards acrylics as they will last longer than brush on enamels like 1 Shot.

That's basically the process we've been using for our Walldog murals that are painted on prepainted
aluminum panels. We've had excellent results.
 
Posted by Bob Sauls (Member # 11321) on :
 
They are pretty slick and hard finishes. Definately scuff and clean before painting with oilbased or acrylics. I recently was walked through some issues on a job by Bill and others. Scotchbright pads are good enough and did not cut all the way through the factory color for me. Then a couple of coats of the ClearShild after hand lettering.
 
Posted by Rodger MacMunn (Member # 4316) on :
 
We've been doing small murals on DiBond, Alupanel & Alucobest for years with acrylics. The people at DiBond told me a few years back that they were using a "polyester" paint, not an enamel. I'm not sure what Alumicore is though ..... is that what they call that half-breed stuff that's part Coroplast? I cut myself really bad on that crap once in a friend's shop.

Acrylics will, as Dave Sherby pointed out, take up to 30 days to dry "hard" & until that happens, can be easily scraped off. If you scotchbrite the surface & get a good bond from either a waterbased or oil based primer ( let it dry for 24 - 48 hours), then your acrylic topcoat will dry a bit faster.

I agree with Bill & Bob, except I like to give it a thin coat of primer too.

OP, ain't automotive paint hard on your brushes?

[ July 10, 2014, 07:28 PM: Message edited by: Rodger MacMunn ]
 
Posted by Rusty Bradley (Member # 6938) on :
 
Thanks for all the info guys...this info set my artist friend's mind at ease when I told her...she said to tell you guys thanks too.
 
Posted by Bob Sauls (Member # 11321) on :
 
In most applications I do prime. The particular job I was doing called for a red background on which I hand lettered. On my first attempt the 1Shot would scrape off quite easily. I scuffed on the redo. I chose the factory red with the thought that it would hold up in the extremes better than OneShot or an acrylic. Because of the necessary scuffing I had to follow with the clearshield to bring back the gloss.
 


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